1. Field of the Invention
The present invention relates generally to the field of bearings and the temperature control of such bearings. More particularly, the invention relates to a novel arrangement for simply and economically cooling a bearing and/or the lubricant of a bearing by enhancing the heat dissipation from the bearing housing.
2. Description of the Related Art
A wide variety of bearings are available and are currently in use throughout a range of industrial applications. Bearings are generally used for facilitation of rotational movement in a mechanical application. In general, a typical bearing includes a plurality of bearing elements situated in a housing. Depending upon the application and the anticipated loading, the bearing elements may be journal bearings, needle bearings, roller bearings, ball bearings, and so forth.
A journal bearing is formed from a plain cylindrical or profiled sleeve that carries a rotating shaft. Journal bearings are sometimes referred to as fluid film bearings because of the presence of a small film of lubricant formed between the cylindrical sleeve and the rotating shaft. The coefficient of friction experienced by the rotating shaft is dependent on whether a fluid film is fully developed. In essence, a fully developed fluid film creates a hydrodynamic pressure sufficient to float the shaft and its respective load relative to the sleeve or journal. The result of a fully developed fluid film is that there is no physical contact between the rotating shaft and the journal during operation. Proper development of a fluid film is dependent upon adequate lubrication of the bearing journal. 
Another bearing type, antifriction bearings, rely on bearing elements disposed between inner and outer rings or races. In these bearings, too, lubrication is important to reduce the coefficient of friction between the component parts. The lubricant also aids in cooling the bearing elements and carrying away contaminants or small debris which may find their way into the bearing or which may be released from the component parts over time.
Adequate lubrication has other related and consequential benefits in addition to proper fluid film development. For example, it is commonplace to equip a bearing with a means for lubricating the bearing elements during operation to prolong the useful life of the bearings. This is typically accomplished by providing a synthetic or mineral grease or oil to coat the surfaces of the bearing elements. The application of grease or oil serves to preclude the ingress of contaminants, such as dirt, debris, moisture, and so forth into the bearing. In some applications the application of oil is accomplished by use of an oil ring. An oil ring hangs loosely over a shaft and rotates as the shaft rotates due to the ring's contact with the shaft. Lubricant is carried from an oil sump to the shaft, then to the bearing surface or liner. Another method is to use a circulating oil system wherein a pressurized lubricant is supplied directly to the bearing surface or liner. In other applications, a pressurized oil mist may be circulated through a bearing cavity to provide continuous lubrication of the bearing. Each lubrication method operates to prevent the ingress of contaminants, while flushing the bearing cavity of contaminants and moisture.
As noted above, another advantage provided by proper lubrication is the cooling of the bearing during operation. In certain fluid film bearings, an oil ring hangs loosely from the shaft into a lubricant bath. The bath is formed in a lower region of the bearing housing often referred to as the oil sump. The rotation of the shaft induces a rotation in the oil ring. The oil ring thus travels through the oil sump causing some of the lubricant to adhere. The lubricant then disperses onto the surface of the shaft and eventually drains back down into the oil sump below. Heat, generated between the shaft and the bearing or conducted by the shaft or bearing, is transferred to the lubricant, which drains to the oil sump and transfers  the heat to the bath. Heat is typically removed from the bath in one of two ways. The heat may be transferred from the oil bath through the bearing housing by conduction, and then to the atmosphere by convection. This method of dissipating heat by convection may be limited by the design of the housing as well as the ambient temperature of the atmosphere relative to the temperature of the bearing housing. The alternative to convection is to use a circulating oil system. Such systems can, however, add significantly to the cost of the installation and to the maintenance required for its upkeep.
A circulating oil system is an effective means of removing heat from a bearing. A circulating oil system takes the lubricant from the oil sump and passes it through a heat exchanger. The lubricant in the oil sump is thus repetitively or continuously removed and replenished with cooled lubricant. Circulating oil systems also may employ other features such as filtration. Filtration keeps the lubricant in a useable condition for a longer period of time. Filtration also helps to keep contaminants from being introduced, or re-introduced, to the bearing elements. However, as previously noted, oil circulation systems are often expensive and can require additional maintenance.
A number of advantages are offered by effective control of the temperature of bearings. The principle advantage is that the shaft and/or bearing elements may become damaged by operation at elevated temperatures. Likewise, lubrication is adversely affected by elevated temperatures. Lubricants are chosen according to certain criteria, one of them being an anticipated or calculated operating temperature range. If the lubricant is exposed to temperatures outside of the specified range, the effectiveness of the lubricant may be greatly diminished. If, for example, a lubricant exceeds the recommended upper temperature limit, the viscosity of the lubricant may be reduced, the lubricant itself may be degraded, and the bearing elements and shaft may experience a greater amount of friction, and ultimately even more heat will be generated. Thus, operating temperature is an important factor in the proper operation of a bearing. 
There is a need, therefore, for an improved technique for efficiently and effectively removing heat from a bearing. There is also a need for a cooling system for bearings that can be installed on new bearings as well as easily retrofitted on existing bearings.